The present invention is directed to a miniaturized stabilized power supply device, such as a switching power supply, and a method for manufacturing such a device. A passive part, including a charge storage film element and a magnetic inductive film element, is formed into a passive part laminate in the shape of a flat board. An active part, formed into a flip chip including semiconductor elements such as transistors and diodes, is mounted on an upper surface of the passive part laminate.
Stabilized power supply devices are known. Conventional stabilized power supply devices are generally constructed by mounting semiconductor elements, such as transistors and diodes, charge storage film elements, such as resistors and capacitors, and magnetic inductive film elements, such as reactances and transformers, on a resin printed circuit board.
A hybrid integrated circuit is generally used for devices of comparatively small capacity but large quantity, in which a ceramic printed circuit board is used instead of the resin printed circuit board. In addition, semiconductors and integrated circuits are mounted on the ceramic printed circuit board as bare chips. Also included are a charge storage film element and a magnetic inductive film element which are generally surface mounted on the hybrid integrated circuit.
However, in attempts to downsize (miniaturize) conventional power supply devices, the passive part laminate, in particular the magnetic inductive film element, is usually disposed behind the active part by utilizing semiconductor technology.
Japanese Laid Open Patent Application No. S60-136363, No. H02-262308, and No. H02-177406 contain a brief review of the prior art attempts at miniaturizing conventional power supply devices by forming coils and magnetic circuits containing thin film structures. Marginally successful attempts at producing miniaturized elements such as transformers and methods for forming coil type inductors on substrates similar to those for integrated circuits are disclosed in Japanese Open Patent Application No. S60-136363. However, the attempts at substantially downsizing conventional power supply devices have been unsuccessful.
Similarly, Japanese Laid Open Patent Publication No. 2-177406 presents attempts at downsizing conventional power supply devices by including the use of a thin film inductance element exhibiting a high inductance value. According to this publication, the film inductance element is equipped with a winding conductor part, formed flatly on a conductor substrate, a signal output conductor part, a signal output conductor part, an insulator that insulates the signal input conductor, and a superconductor film laminate. The insulating film, arranged between a plurality of superconductor films, is provided at the center of the winding conductor, and the semiconductor films have independent windings for current applications.
By way of an example, the reference discloses a superconductor film laminate equipped with two layers of thin superconductor films that is insulated by an insulating film of MgO containing YBa.sub.2 Cu.sub.2 Ox. No attempts are made at downsizing conventional power supply devices similar to the present invention.
Similarly, Japanese laid Open Patent Application No. 2-262308 is directed at a plane indicator, in which a large inductance is achieved simultaneously with a small load current. According to this publication, a necessary inductance can be obtained, with a large load current, by means of a high permeability magnetic substance with a large magnetic flux saturation density on both sides of spiral type coil insulating layers.
The miniaturization of passive part laminates of conventional stabilized power supply devices, including magnetic inductive film elements and charge storage film elements, has been attempted by using the aforementioned thin film structure.
In recent years, an increase in the demand for substantially cheap and small electronic devices has in turn created a demand for miniaturized electronic components together with a reduction in the overall cost of conventional stabilized power supply devices. Indeed, the demand for smaller devices at low cost has been growing steadily. This demand in turn has created a demand for effective stabilized power supply devices which can be adopted for use in smaller electronic devices.
However, the demand for smaller stabilized power supply devices effective for use in miniaturized electronic devices has not been met. Attempts at adapting existing components for use in miniaturized electronic devices have been unsuccessful and have resulted in the surface-mounting of active parts of semiconductor devices and the passive parts of discrete elements on the hybrid integrated circuit.
However, surface mounting requires an extensive area for mounting conventional semiconductor chips and elements. This method also uses the area underneath the mounted chips for wiring the various components. The surface mounting method leaves a lot to be desired in that it fails to effectively utilize the space provided. Indeed, the surface mounting method requires substantial space, which defeats the whole purpose of miniaturizing conventional electronic components.